Telecommunications network

ABSTRACT

A system and method for controlling on a worldwide basis two or more telecommunications networks which are themselves capable of exercising a form of common channel signaling network control. The system uses an architecture in which a destination telecommunications network having common channel signaling control is connected to an originating telecommunications network having common signaling control through a call set up and control methodology which provides ad hoc connection between the two spaced telecommunication networks and common channel signaling networks via an unrelated world wide data network which preferably constitutes the Internet.

TECHNICAL FIELD

[0001] The present invention relates to a telecommunications network andmore particularly relates to a public switched telecommunicationsnetwork having a control signaling system which provides wide areanational and international routing and supervision using out of bandsignaling which includes a virtual common channel signaling system whichdoes not require an end to end exchange of data messages using aconnection oriented mode of signaling. The following background materialintroduces various telephone network control and computer networkconcepts and definitions and those familiar with telephone networkcontrol and computer networks and TCP/IP may wish to skip to followingsubsections.

[0002] Acronyms

[0003] The written description uses a large number of acronyms to referto various services, messages and system components. Although generallyknown, use of several of these acronyms is not strictly standardized inthe art. For purposes of this discussion, acronyms therefore will bedefined as follows:

[0004] Address Complete Message (ACM)

[0005] Advanced Intelligent Network (AIN)

[0006] Answer Message (ANM)

[0007] Application Service Part (ASP)

[0008] Backward Indicator Bit (BIB)

[0009] Backward Sequence Number (BSN)

[0010] Central Office (CO)

[0011] Common Channel Signaling (CCS)

[0012] Common Channel Interoffice Signaling (CCIS)

[0013] Customer Identification Code (CIC)

[0014] Cyclic Redundancy Code (CRC)

[0015] Data and Reporting System (DRS)

[0016] Destination Point Code (DPC)

[0017] Dual Tone Multifrequency (DTMF)

[0018] Fill in Signal Unit (FISU)

[0019] Global Title (GTT)

[0020] Initial Address Message (IAM)

[0021] Integrated Service Control Point (ISCP)

[0022] Integrated Services Digital Network (ISDN)

[0023] ISDN User Part (ISDN-UP)

[0024] International Standards Organization (ISO)

[0025] Link Service Signaling Unit (LSSU)

[0026] Local Access and Transport Area (LATA)

[0027] Message Signaling Unit (MSU)

[0028] Message Transfer Part (MTP)

[0029] Multi-Services Application Platform (MSAP)

[0030] Open Systems Interconnection (OSI)

[0031] Operations, Maintenance, Application Part (OMAP)

[0032] Origination Point Code (OPC)

[0033] Point in Call (PIC)

[0034] Point in Routing (PIR)

[0035] Point of Presence (POP)

[0036] Recent Change (RC)

[0037] Service Control Point (SCP)

[0038] Service Creation Environment (SCE)

[0039] Service Information Octet (SIO)

[0040] Service Management System (SMS)

[0041] Service Switching Point (SSP)

[0042] Signaling Connection Control Part (SCCP)

[0043] Signaling Link Selection (SLS)

[0044] Signaling System 7 (SS7)

[0045] Signaling Point (SP)

[0046] Signaling Transfer Point (STP)

[0047] Subsystem Number (SSN)

[0048] Time Slot Interchange (TSI)

[0049] Transaction Capabilities Applications Protocol (TCAP)

BACKGROUND

[0050] Computer Network Background

[0051] A computer network is simply a collection of autonomous computersconnected together to permit sharing of hardware and software resources,and to increase overall reliability. The qualifying term “local area” isusually applied to computer networks in which the computers are locatedin a single building or in nearby buildings, such as on a college campusor at a single corporate site. When the computers are further apart, theterms “wide area network” or “long haul network” are used, but thedistinction is one of degree and the definitions sometimes overlap.

[0052] A bridge is a device that is connected to at least two LANs andserves to pass message frames or packets between LANs, such that asource station on one LAN can transmit data to a destination station onanother LAN, without concern for the location of the destination.Bridges are useful and necessary network components, principally becausethe total number of stations on a single LAN is limited. Bridges can beimplemented to operate at a selected layer of protocol of the network. Adetailed knowledge of network architecture is not needed for anunderstanding of this invention, but a brief description follows by wayof further background.

[0053] At the heart of any computer network is a communication protocol.A protocol is a set of conventions or rules that govern the transfer ofdata between computer devices. The simplest protocols define only ahardware configuration, while more complex protocols define timing, dataformats, error detection and correction techniques and softwarestructures.

[0054] Computer networks almost universally employ multiple layers ofprotocols. A low-level physical layer protocol assures the transmissionand reception of a data stream between two devices. Data packets areconstructed in a data link layer. Over the physical layer, a network andtransport layer protocol governs transmission of data through thenetwork, thereby ensuring end-to end reliable data delivery.

[0055] The most common physical networking protocol or topology forsmall networks is Ethernet, developed by Xerox. When a node possesses apacket to be transmitted through the network, the node monitors thebackbone and transmits when the backbone becomes clear. There is nocentral backbone master device to grant requests to gain access to thebackbone. While this type of multipoint topology facilitates rapidtransmission of data when the backbone is lightly utilized, packetcollisions may occur when the backbone is heavily utilized. In suchcircumstances, there is a greater chance that multiple nodes will detectthat the backbone is clear and transmit their packets coincidentally. Ifpackets are impaired in a collision, the packets are retransmitted untiltransmission is successful.

[0056] Another conventional physical protocol or topology is Token Ring,developed by IBM. This topology employs a “token” that is passedunidirectionally from node to node around an annular backbone. The nodepossessing the token is granted exclusive access to the backbone for asingle packet transfer. While this topology reduces data collisions, thelatency incurred while each node waits for the token translates into aslower data transmission rate than Ethernet when the network is lightlyutilized.

[0057] As computer networks have developed, various approaches have beenused in the choice of communication medium, network topology, messageformat, protocols for channel access, and so forth. Some of theseapproaches have emerged as de facto standards, but there is still nosingle standard for network communication. However, a model for networkarchitectures has been proposed and widely accepted. It is known as theInternational Standards Organization (ISO) Open Systems Interconnection(OSI) reference model. The OSI reference model is not itself a networkarchitecture. Rather it specifies a hierarchy of protocol layers anddefines the function of each layer in the network. Each layer in onecomputer of the network carries on a conversation with the correspondinglayer in another computer with which communication is taking place, inaccordance with a protocol defining the rules of this communication. Inreality, information is transferred down from layer to layer in onecomputer, then through the channel medium and back up the successivelayers of the other computer. However, for purposes of design of thevarious layers and understanding their functions, it is easier toconsider each of the layers as communicating with its counterpart at thesame level, in a “horizontal” direction.

[0058] The lowest layer defined by the OSI model is called the physicallayer, and is concerned with transmitting raw data bits over thecommunication channel. Design of the physical layer involves issues ofelectrical, mechanical or optical engineering, depending on the mediumused for the communication channel. The layer next to the physical layeris called the data link layer. The main task of the data link layer isto transform the physical layer, which interfaces directly with thechannel medium, into a communication link that appears error-free to thenext layer above, known as the network layer. The data link layerperforms such functions as structuring data into packets or frames, andattaching control information to the packets or frames, such aschecksums for error detection, and packet numbers.

[0059] Although the data link layer is primarily independent of thenature of the physical transmission medium, certain aspects of the datalink layer function are more dependent on the transmission medium. Forthis reason, the data link layer in some network architectures isdivided into two sublayers: a logical link control sublayer, whichperforms all medium-independent functions of the data link layer, and amedia access control (MAC) sublayer. This sublayer determines whichstation should get access to the communication channel when there areconflicting requests for access. The functions of the MAC layer are morelikely to be dependent on the nature of the transmission medium.

[0060] Bridges may be designed to operate in the MAC sublayer. Furtherdetails may be found in “MAC Bridges,” P802.1D/D6, September 1988, adraft publication of IEEE Project 802 on Local and Metropolitan AreaNetwork Standards, or in later drafts of this document.

[0061] The basic function of a bridge is to listen “promiscuously,”i.e., to all message traffic on all LANs to which it is connected, andto forward each message it hears onto LANs other than the one from whichthe message was heard. Bridges also maintain a database of stationlocations, derived from the content of the messages being forwarded.Bridges are connected to LANs by paths known as “links.” After a bridgehas been in operation for some time, it can associate practically everystation with a particular link connecting the bridge to a LAN, and canthen forward messages in a more efficient manner, transmitting only overthe appropriate link. The bridge can also recognize a message that doesnot need to be forwarded, because the source and destination stationsare both reached through the same link. Except for its function of“learning” station locations, or at least station directions, the bridgeoperates basically as a message repeater.

[0062] As network topologies become more complex, with large numbers ofLANs, and multiple bridges interconnecting them, operationaldifficulties can ensue if all possible LAN bridging connections arepermitted. In particular, if several LANs are connected by bridges toform a closed loop, a message may be circulated back to the LAN fromwhich it was originally transmitted, and multiple copies of the samemessage will be generated. In the worst case, messages will beduplicated to such a degree that the networks will be effectivelyclogged with these messages and unable to operate at all.

[0063] To prevent the formation of closed loops in bridged networks,IEEE draft publication P802.1D, referred to above, proposes a standardfor a spanning tree algorithm that will connect the bridged network intoa tree configuration, containing no closed loops, and spanning theentire network configuration. The spanning tree algorithm is executedperiodically by the bridges on the interconnected network, to ensurethat the tree structure is maintained, even if the physicalconfiguration of the network changes. Basically, the bridges execute thespanning tree algorithm by sending special messages to each other toestablish the identity of a “root” bridge. The root bridge is selected,for convenience, as the one with the smallest numerical identification.The algorithm determines which links of the bridges are to be active andwhich are to be inactive, i.e., disabled, in configuring the treestructure. One more piece of terminology is needed to understand how thealgorithm operates. Each LAN has a “designated” link, which means thatone of the links connectable to the LAN is designated to carry traffictoward and away from the root is bridge. The basis for this decision issimilar to the basis for selecting the root bridge. The designated linkis the one providing the least costly (shortest) path to the rootbridge, with numerical bridge identification being used as atie-breaker. Once the designated links are identified, the algorithmchooses two types of links to be activated or closed: first, for eachLAN its designated link is chosen, and second, for each bridge a linkthat forms the “best path” to the root bridge is chosen, i.e., a linkthrough which the bridge received a message giving the identity of theroot bridge. All other links are inactivated. Execution of the algorithmresults in interconnection of the LANs and bridges in a tree structure,i.e., one having no closed loops.

[0064] The “Internet” is a collection of networks, including Arpanet,NSFnet, regional networks such as NYsernet, local networks at a numberof university and research institutions, and a number of militarynetworks. The protocols generally referred to as TCP/IP were originallydeveloped for use only through Arpanet and have subsequently becomewidely used in the industry. The protocols provide a set of servicesthat permit users to communicate with each other across the entireInternet. The specific services that these protocols provide are notimportant to the present invention, but include file transfer, remotelog-in, remote execution, remote printing, computer mail, and access tonetwork file systems.

[0065] The basic function of the Transmission Control Protocol (TCP) isto make sure that commands and messages from an application protocol,such as computer mail, are sent to their desired destinations. TCP keepstrack of what is sent, and retransmits anything that does not get to itsdestination correctly. If any message is too long to be sent as one“datagram,” TCP will split it into multiple datagrams and makes surethat they all arrive correctly and are reassembled for the applicationprogram at the receiving end. Since these functions are needed for manyapplications, they are collected into a separate protocol (TCP) ratherthan being part of each application. TCP is implemented in the transportlayer of the OSI reference model.

[0066] The Internet Protocol (IP) is implemented in the network layer ofthe OSI reference model, and provides a basic service to TCP: deliveringdatagrams to their destinations. TCP simply hands IP a datagram with anintended destination; IP is unaware of any relationship betweensuccessive datagrams, and merely handles routing of each datagram to itsdestination. If the destination is a station connected to a differentLAN, the IP makes use of routers to forward the message.

[0067] TCP/IP frequently uses a slight deviation from the seven-layerOSI model in that it may have five layers. These five layers arecombinations and derivatives of the seven-layer model as shown inFIG. 1. The five layers are as follows:

[0068] Layer 5—The Application Layer. Applications such as ftp, telnet,SMTP, and NFS relate to this layer.

[0069] Layer 4—The Transport Layer. In this layer, TCP and UDP addtransport data to the packet and pass it to layer 3.

[0070] Layer 3—The Internet Layer. When an action is initiated on alocal host (or initiating host) that is to be performed or responded toon a remote host (or receiving host), this layer takes the package fromlayer 4 and adds IP information before passing it to layer 2.

[0071] Layer 2—The Network Interface Layer. This is the network deviceas the host, or local computer, sees it and it is through this mediumthat the data is passed to layer 1.

[0072] Layer 1—The Physical Layer. This is literally the Ethernet orSerial Line Interface Protocol (SLIP) itself.

[0073] At the receiving host the layers are stripped one at a time, andtheir information is passed to the next highest level until it againreaches the application level. If a gateway exists between theinitiating and receiving hosts, the gateway takes the packet from thephysical layer, passes it through a data link to the IP phvsical layerto continue, as is shown in FIG. 2. As a message is sent from the firsthost to the second, gateways pass the packet along by stripping offlower layers, readdressing the lower layer, and then passing the packettoward its final destination.

[0074] A router, like a bridge, is a device connected to two or moreLANs. Unlike a bridge, however, a router operates at the network layerlevel, instead of the data link layer level. Addressing at the networklayer level makes use of a 32-bit address field for each host, and theaddress field includes a unique network identifier and a host identifierwithin the network. Routers make use of the destination networkidentifier in a message to determine an optimum path from the sourcenetwork to the destination network. Various routing algorithms may beused by routers to determine the optimum paths. Typically, routersexchange information about the identities of the networks to which theyare connected.

[0075] When a message reaches its destination network, a data link layeraddress is needed to complete forwarding to the destination host. Datalink layer addresses are 48 bits long and are globally unique, i.e., notwo hosts, wherever located, have the same data link layer address.There is a protocol called ARP (address resolution protocol), whichobtains a data link layer address from the corresponding network layeraddress (the address that IP uses). Typically, each router maintains adatabase table from which it can look up the data link layer address,but if a destination host is not in this ARP database, the router cantransmit an ARP request. This message basically means: “will the hostwith the following network layer address please supply its data linklayer address.” only the addressed destination host responds, and therouter is then able to insert the correct data link layer address intothe message being forwarded, and to transmit the message to its finaldestination.

[0076] IP routing specifies that IP datagrams travel throughinternetworks one hop at a time (next hop routing) based on thedestination address in the IP header. The entire route is not known atthe outset of the journey. Instead, at each stop, the next destination(or next hop) is calculated by matching the destination address withinthe datagram's IP header with an entry in the current node's (typicallybut not always a router) routing table.

[0077] Each node's involvement in the routing process consists only offorwarding packets based on internal information resident in the router,regardless of whether the packets get to their final destination. Toextend this explanation a step further, IP routing does not alter theoriginal datagram. In particular, the datagram source and destinationaddresses remain unaltered. The IP header always specifies the IPaddress of the original source and the IP address of the ultimatedestination.

[0078] When IP executes the routing algorithm it computes a new address,the IP address of the machine/router to which the datagram should besent next. This algorithm uses the information from the routing tableentries, as well as any cached information local to the router. This newaddress is most likely the address of another router/gateway. If thedatagram can be delivered directly (the destination network is directlyattached to the current host) the new address will be the same as thedestination address in the IP header.

[0079] The next hop address defined by the method above is not stored intheir IP datagram. There is no reserved space to hold it and it is not“stored” at all. After executing the routing algorithm (the algorithm isspecific to the vendor/platform) to define the next hop address to thefinal destination. The IP protocol software passes the datagram and thenext hop address to the network interface software responsible for thephysical network over which the datagram must now be sent.

[0080] The network interface software binds the next hop address to aphysical address (this physical address is discovered via addressresolution protocols (ARP, RARP, etc.), forms a frame (Ethernet, SMDS,FDDI, etc.—OSI layer 2 physical address) using the physical address,places the datagram in the data portion of the frame, and sends theresult out over the physical network interface through which the nexthop gateway is reached. The next gateway receives the datagram and theforegoing process is repeated.

[0081] In addition, the IP does not provide for error reporting back tothe source when routing anomalies occur. This task is left to anotherInternet protocol, the Internet Control Message Protocol (ICMP).

[0082] A router will perform protocol translation. One example is atlayers 1 and 2. If the datagram arrives via an Ethernet interface and isdestined to exit on a serial line, for example, the router will stripoff the Ethernet header and trailer, and substitute the appropriateheader and trailer for the specific network media, such as SMDS, by wayof example.

[0083] A route policy may be used instead of routing table entries toderive the next hop address. In the system and methodology of thepresent invention, the source address is tested to see in which ISPaddress range it falls. Once the ISP address range is determined thepacket is then routed to the next hop address associated with thespecific ISP.

[0084] Data communications network services have two categories of callestablishment procedures: connection-oriented and connectionless.

[0085] Connection-oriented network services require that users establisha single distinct virtual circuit before the data can be transmitted.This circuit then defines a fixed path through the network that alltraffic follows during the session. Several packet switching servicesare connection-oriented, notably X.25 and Frame Relay. X.25 is theslower of the services, but has built-in error correction—enough for itsperformance not to depend on clean, high-quality optical fiber lines.Frame relay, regarded as the first generation of fast packet technology,is well-suited for high-speed bursty data communication applications.

[0086] Connectionless network services, by contrast, let each packet ofa communications session take a different, independent path through thenetwork. One example is the Switched Multimegabit Data Service (SMDS), apossible precursor to broadband ISDN. This fast-packet service supportsdata rates ranging from the T1 rate of 1.544 Mb/s up to 1 Gb/s. The SMDStransport system architecture is defined by IEEE 802.6 Metropolitan AreaNetwork standards.

[0087] Eventually, SMDS is expected to operate at rates of 51.85 Mb/s to9.953 Gb/s specified by the family of standards known in North Americaas Synchronous Optical Network (SONET). Synchronous Digital Hierarchy(SDH) is an ITU recommendation that grew out of and includes thespecifications of SONET.

[0088] The process of routing packets over the Internet is alsoconsidered a connectionless network service. The Internet Protocol (IP)addresses packets from sender to receiver. It is still used mostly inconjunction with the Transmission Control Protocol (TCP), whichestablishes a connection between end users to manage the traffic flowand ensures the data are correct, providing end-to-end reliability. Thecombination, known as TCP/IP, is the Internet's main backbone protocolsuite.

[0089] Telephone Network Control

[0090] All telecommunications systems having multiple switching officesrequire signaling between the offices. Telephone networks requiresignaling between switching offices for transmitting routing anddestination information, for transmitting alerting messages such as toindicate the arrival of an incoming call, and for transmittingsupervisor information, e.g., relating to line status. Signaling betweenoffices can use ‘in-band’ transport or ‘out-of-band’ transport.

[0091] In-band signaling utilizes the same channel that carries thecommunications of the parties. In a voice telephone system, for example,one of the common forms of in-band signaling between offices utilizesmulti-frequency signaling over voice trunk circuits. The same voicetrunk circuits also carry the actual voice traffic between switchingoffices. In-band signaling, however, tends to be relatively slow andties up full voice channels during the signaling operations. Intelephone call processing, a substantial percentage of all calls gounanswered because the destination station is busy. For in-bandsignaling, the trunk to the end office switching system serving thedestination is set-up and maintained for the duration of signaling untilthat office informs the originating office of the busy line condition.As shown by this example, in-band signaling greatly increases congestionon the traffic channels, that is to say, the voice channels in the voicetelephone network example. In-band signaling also is highly susceptibleto fraud because hackers have developed devices which mimic in-bandsignaling.

[0092] Out-of-band signaling evolved to mitigate the problems of in-bandsignaling. Out-of-band signaling utilizes separate channels, and in manycases separate switching elements. As such, out-of-band signalingreduces congestion on the channels carrying the actual communicationtraffic. Also, messages from the end users always utilize an in-bandformat and remain in-band, making it virtually impossible for an enduser to simulate signaling messages which ride on an out-of-band channelor network. Out-of-band signaling utilizes its own signal formats andprotocols and is not constrained by protocols and formats utilized forthe actual communication, therefore out-of-band signaling typically isconsiderably faster than in-band signaling.

[0093] Out of band signaling networks typically include data links andone or more packet switching systems. Out-of-band signaling fortelephone networks is often referred to as Common Channel Signaling(CCS) or Common Channel Interoffice Signaling (CCIS). Most suchsignaling communications for telephone networks utilizes signalingsystem 7 (SS7) protocol. An SS7 compliant CCIS network comprises dataswitching systems designated Signal Transfer Points (STPs) and datalinks between the STPs and various telephone switching offices of thenetwork. In advanced versions of the telephone network including highlevel control nodes, identified as Service Control Points (SCPs) orIntegrated Service Control Points (ISCPs), the CCIS network alsoincludes data links connecting the high level control nodes to one ormore of the STPs.

[0094] The STPs are program controlled packet data switching systems. Inoperation, an STP will receive a packet data message from another nodeof the network, for example from an end office switching system. The STPanalyzes point code information in the packet and routes the packetaccording to a translation table stored within the STP. This translationtable is static. Any packet having a particular point code is output ona port going to the next CCIS signaling node specified by translation ofthat point code.

[0095] The development of the CCIS network has recently permitted theoffering of a number of new service features provided by centralizedprogram control from a high level control point. Such an enhancedtelephone network is often termed an Advanced Intelligent Network (AIN).In an AIN type system, local and/or toll offices of the public telephonenetwork detect one of a number of call processing events identified asAIN “triggers”. For ordinary telephone service calls, there would be noevent to trigger AIN processing; and the local and toll office switcheswould function normally and process such calls without referring to thecentral database for instructions. An office which detects a triggerwill suspend call processing, compile a call data message and forwardthat message via the CCIS signaling network to an Integrated ServiceControl Point (ISCP) which includes a Multi-Services ApplicationPlatform (MSAP) database. If needed, the ISCP can instruct the centraloffice to obtain and forward additional information. Once sufficientinformation about the call has reached the ISCP, the ISCP accesses itsstored data tables in the MSAP database to translate the receivedmessage data into a call control message and returns the call controlmessage to the office of the network via CCIS link. The network officesthen use the call control message to complete the particular call. AnAIN type network for providing an Area Wide Centrex service wasdisclosed and described in detail in commonly assigned U.S. Pat. No.5,247,571 to Kay et al., the disclosure of which is entirelyincorporated herein by reference.Existing AIN type systems, such asdisclosed in the Kay et al. Patent, utilize the routing functionality ofthe STPs in the CCIS network as described above. Every time a specifiedswitching office launches a query for an identified ISCP, thetranslation table in the STP(s) of the CCIS network causes the STP(s) toroute the query message to that ISCP.

[0096] The CCIS and AIN which have been described provide effective andefficient connection oriented signaling between switches in moderntelephone networks. However, such control is not available in the UnitedStates on a nationwide basis and is not available internationally for avariety of reasons. Connections between Interexchange Carriers (IXCs)and Local Exchange Carriers (LECs) in the United States are still madeto a significant extent with in-band signaling. This requiresinefficient use of circuit time of voice trunks and is vulnerable tofraud. The inefficiencies are particularly aggravated whereinternational and particularly transoceanic communications are involved.

DISCLOSURE OF THE INVENTION OBJECTS OF INVENTION

[0097] It is an object of the present invention to provide telephoneservice over wide areas between different telephone systems and carriersusing a new form of common channel signaling architecture which permitsuse of existing telecommunication signaling control facilities inconjunction with existing and readily available world wideconnectionless data networks.

[0098] It is a further object of the invention to provide such atelecommunications system and service in a manner which obviates anyneed for installation of end to end connection oriented common channelsignaling facilities.

[0099] It is another object of the invention to provide telephoneservice over wide areas between different telephone systems and carriersusing common channel signaling which uses existing telecommunicationcontrol facilities in conjunction with existing open access,non-proprietary world widedata networks.

[0100] It is a still further object of the invention to provide a newmethod and system utilizing an architecture in which a destinationtelecommunications network having common channel signaling control isconnected to an originating telecommunications network having commonsignaling control through a call set up methodology which provides adhoc connection between the two spaced common channel signaling networksvia an unrelated world wide data network which preferably constitutesthe Internet.

[0101] Additional objects, advantages and novel features of theinvention will be set forth in part in the description which follows,and in part will become apparent to those skilled in the art uponexamination of the following or may be learned by practice of theinvention. The objects and advantages of the invention may be realizedand attained by means of the instrumentalities and combinationsparticularly pointed out in the appended claims.

SUMMARY OF THE INVENTION

[0102] The present invention provides a novel system and method forcontrolling on a worldwide basis two or more telecommunications networkswhich are themselves capable of exercising a form of common channelsignaling network control. The new system and method do not require thatthe controlled networks be adjoining, nor do they require that they belinked by intervening networks which have common channel signalingnetwork control. The invention is particularly advantageous in providingtelecommunications connectings between transoceanic networks. The newmethod and system use an architecture in which a destinationtelecommunications network having common channel signaling control isconnected to an originating telecommunications network having commonsignaling control through a call set up methodology which provides adhoc connection between the two spaced common channel signaling networksvia an unrelated world wide data network which preferably constitutesthe Internet. Through this arrangement the normal CCIS signaling of thetwo spaced networks can be effectively utilized virtually without changeto obtain the advantages of common channel signaling which are known tothose skilled in the art. The invention provides multiple embodimentsand permits call set up with virtually no usage of common channelsignaling in the originating telecommunications network. According toanother embodiment the advance features of an Advanced IntelligentNetwork (AIN) may be provided from a central control extraneous to thetwo telecommunications networks.

DESCRIPTION OF THE DRAWINGS

[0103]FIG. 1 is a comparative diagram of the International StandardsOrganization (ISO) Open System Interconnection (OSI) model for networkarchitectures and a commonly used TCP/IP model.

[0104]FIG. 2 is a simplified block diagram illustrating the passage of apacket from an initiating host to a receiving host through a gatewayusing the TCP/IP model.

[0105]FIG. 3 is a simplified block diagram of a Public SwitchedTelephone Network and its SS7 signal control network.

[0106]FIG. 4 depicts the protocol stack for SS7 and comparison thereofto the OSI model.

[0107]FIG. 5 illustrates in graphic form the layout of an SS7 protocolmessage packet.

[0108]FIG. 6 illustrates in graphic form the layout of the routing labelportion of the SS7 protocol message packet shown in FIG. 5.

[0109]FIGS. 7A and 7B together show a somewhat more detailed blockdiagram of the network, i.e., including two interexchange carriernetworks.

[0110]FIG. 8 is a more detailed diagram of one of the switching systems.

[0111]FIG. 9 is a more detailed diagram of one of the signal transferpoints.

[0112]FIG. 10 is a more detailed diagram of an integrated signal controlpoint.

[0113]FIG. 11 is a simplified diagram of illustrating the architectureof the existing public switched telephone network (PSTN) in the UnitedStates as currently utilized for a typical transoceanic telephonecommunication.

[0114]FIG. 12 is a simplified diagram of illustrating the architectureof the existing public switched telephone network (PSTN) in the UnitedStates modified according to one embodiment of the invention toimplement a transoceanic telephone communication.

[0115]FIG. 13 shows in diagrammatic form the functional architecture ofone embodiment of an Internet Module for use in the system illustratedin FIG. 11.

[0116]FIG. 14 is a simplified diagram of the Internet.

[0117]FIG. 15 is a simplified diagram illustrating another embodiment ofthe invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0118] To facilitate understanding of the present invention, it will behelpful first to review the architecture and operation of a telephonenetwork having CCIS capabilities.

[0119] Referring to FIG. 3 there is shown a simplified block diagram ofa switched traffic network and the common channel signaling network usedto control the signaling for the switched traffic network. In theillustrated example, the overall network actually comprises two separatenetworks 1 and 2. As shown, these networks serve different regions ofthe country and are operated by different local exchange carriers.Alternatively, one network may be a local exchange carrier network, andthe other network may comprise an interexchange carrier network.Although the signaling message routing of the present invention willapply to other types of networks, in the illustrated example, bothnetworks are telephone networks.

[0120] In FIG. 3, a first local exchange carrier network 1 includes anumber of end office. switching systems providing connections localcommunication lines coupled to end users telephone station sets. Forconvenience, only one end office 11 is shown. The first local exchangecarrier network 1 also includes one or more tandem switching systemsproviding connections between offices. For convenience, only one tandemoffice 13 is shown. As such, the first telephone network consists of aseries of switching offices interconnected by voice grade trunks, shownas solid lines. One or more trunks also connect the tandem 13 to one ormore switches, typically another tandem office, in the second network 2.

[0121] Each switching office has SS7 signaling capability and isconventionally referred to as a signaling point (SP) in reference to theSS7 network. In the first network 1, each switching office 11, 13 alsois programmed to recognize identified events or points in call (PICs).In response to a PIC, either office 11 or 13 triggers a query throughthe signaling network to an Integrated Service Control Point (ISCP) forinstructions relating to AIN type services. Switching offices having AINtrigger and query capability are referred to as Service Switching Points(SSPs). The ISCP 17 is an integrated system shown in more detail in FIG.8 and discussed more fully below.

[0122] The end office and tandem switching systems typically consist ofprogrammable digital switches with CCIS communications capabilities. Oneexample of such a switch is a 5ESS type switch manufactured by AT&T; butother vendors, such as Northern Telecom and Siemens, manufacturecomparable digital switches which could serve as the SPs.

[0123] Within the first network 1, the common channel interofficesignaling (CCIS) network includes one or more Signaling Transfer Points(STPs) and data links shown as dotted lines between the STP(s) and theswitching offices. A data link also connects the STP 15 to the ISCP 17.One or more data links also connect the STP(s) 15 in the network 1 tothose in networks of other carriers, for example to the STP 25 in thenetwork 2.

[0124] Although shown as telephones in FIG. 3, the terminal devices cancomprise any communication device compatible with the localcommunication line. Where the line is a standard voice grade telephoneline, for example, the terminals could include facsimile devices, modemsetc.

[0125] The network 2 is generally similar in structure to the network 1.The network 2 includes a number of end office SP type switching systems21 (only one shown) as well as one or more tandem switching systems 23(only one shown). The network 2 includes a CCIS network comprising oneor more STPs 25 and data links to the respective SP type switchingoffices and to the CCIS system of other carriers networks.

[0126] In the illustrated example, the second network 2 is not a fullAIN type network. The switching systems do not have full AIN trigger andquery capabilities. The network 2 includes a Service Control Point (SCP)27, but the routing tables utilized in that database are more limitedthan those in the ISCP 17. The switching systems 21, 23 can query theSCP 27 for routing information, but the range of trigger events are morelimited, e.g., to 800 number call processing.

[0127] An end office switching system 11 or 21 shown in FIG. 3 normallyresponds to a service request on a local communication line connectedthereto, for example an off-hook followed by dialed digit information,to selectively connect the requesting line to another selected localcommunication line. The connection can be made locally through only theconnected end office switching system but typically will go through anumber of switching systems. For example, when a subscriber at station Xcalls station Y, the connection is made through the end office switchingsystem 11, the tandem offices 13 and 23 and the end office switchingsystem 21 through the telephone trunks interconnecting the variousswitching offices.

[0128] In the normal call processing, the central office switchingsystem responds to an off-hook and receives dialed digits from thecalling station. The central office switching system analyzes the.received digits to determine if the call is local or not. If the calledstation is local and the call can be completed through the one centraloffice, the central office switching system connects the calling stationto the called station. If, however, the called station is not local, thecall must be completed through one or more distant central offices, andfurther processing is necessary. If at this point the call wereconnected serially through the trunks and appropriate central officesbetween the caller and the called party using in-band signaling, thetrunks would be engaged before a determination is made that the calledline is available or busy. Particularly if the called line is busy, thiswould unnecessarily tie up limited voice trunk circuit capacity. TheCCIS system through the STP's was developed to alleviate this problem.

[0129] In the CCIS type call processing method, the originating endoffice switching system, switching system 11 in the present example,suspends the call and sends a message through the CCIS network to theend office switching system serving the destination telephone line,i.e., to a terminating end office 21. The terminating end officedetermines whether or not the called station Y is busy. If the calledstation is busy, the terminating end office 21 so informs theoriginating end office 11 via CCIS message, and the originating endoffice provides a busy signal to the calling station. If the calledstation Y is not busy, the terminating end office 21 so informs theoriginating end central office 11. A telephone connection is thenconstructed via the trunks and end offices (and/or tandem offices) ofthe network between the calling and called stations.

[0130] For an AIN type service, such as call redirection based on datastored in the ISCP 17, the end offices and/or tandems are SSP capableand detect one of a number of call processing events, each identified asa ‘point in call’ (PIC), to trigger AIN type processing. Specifically,in response to such a PIC, a tandem 13 or end office switching system 11suspends call processing, compiles a call data message and forwards thatmessage via common channel interoffice signaling (CCIS) links and one ormore STPs 15 to an ISCP 17. If needed, the ISCP 17 can instruct theparticular switching office to obtain and forward additionalinformation. Once sufficient information has reached the ISCP 17, theISCP 17 accesses its stored data tables to translate the received datainto a call control message and returns the call control message to theswitching office via the STP 15 and the appropriate CCIS links. Theoffice uses the call control message to complete the particular callthrough the public switched network in the manner specified by thesubscriber's data file in the ISCP 17.

[0131] The SCP 27 offers a similar capability in the network 2, but therange of service features offered by that database are more limited.Typically, the SCP 27 offers only 800 number calling services with alimited number of related call routing options. The triggeringcapability of the tandem 32 and end office 21 is limited to 800 numberrecognition. If the end office 21 is capable of 800 number recognitionand CCIS communication with the SCP 27, as shown, then the office 21launches a CCIS query to the SCP 27 in response to dialing of an 800number at a station set Y. The SCP 27 translates the dialed 800 numberinto an actual destination number, for example the telephone number ofstation X, and transmits a CCIS response message back to end office 21.End office 21 then routes the call through the public network to thestation X identified by the number sent back by the SCP 27, using CCIScall routing procedures of the type discussed above.

[0132] SS7 signaling protocol is based on the OSI model.

International Standards Organization (ISO) Open Systems Interconnection(OSI) reference model specifies a hierarchy of protocol layers anddefines the function of each layer in the network. FIG. 4 shows the OSImodel and the relationship thereof to the protocol stack for SS7. Thelowest layer defined by the OSI model is the physical layer (L1). Thislayer provides transmission of raw data bits over the physicalcommunication channel through the particular network. The layer next tothe physical layer is the data link layer (L2). The data link layertransforms the physical layer, which interfaces directly with thechannel medium, into a communication link that appears error-free to thenext layer above, known as the network layer (L3). The data link layerperforms such functions as structuring data into packets or frames, andattaching control information to the packets or frames, such aschecksums for error detection, and packet numbers. The network layerprovides capabilities required to control connections between endsystems through the network, e.g., set-up and tear-down of connections.

[0133] In the OSI model, a transport layer protocol (L4) runs above thenetwork layer. The transport layer provides control of data transferbetween end systems. Above the transport layer, a session layer (L5) isresponsible for establishing and managing communication betweenpresentation entities. For example, the session layer determines whichentity communicates at a given time and establishes any necessarysynchronization between the entities.

[0134] Above the session layer, a presentation layer (L6) serves torepresent information transferred between applications in a manner thatpreserves its meaning (semantics) while resolving differences in theactual representation (syntax). A protocol (L7) that is specific to theactual application. that utilizes the information communicated runs atthe top of the protocol stack.

[0135] A detailed explanation of the SS7 protocol may be found in BellCommunications Research, “Specification of Signaling System Number 7,”Generic Requirements, GR-246-CORE, Issue 1, Dec. 1994, the disclosure ofwhich is incorporated herein in its entirety by reference. A summarydescription of the most relevant aspects of SS7 appears below.

[0136] For SS7, typical applications layer protocols include TransactionCapability Application Part (TCAP); Operations, Maintenance, ApplicationPart (OMAP); and ISDN User Part (ISDN-UP). TCAP provides the signalingprotocols for exchange of non-circuit related, transaction-basedinformation, typically for accessing databases such as SCPs. Forexample, TCAP specifies the format and content of an initial querymessage from an SSP to an SCP and various response messages from the SCPback to the SSP. ISDN-UP is the actual call control application protocolof SS7. ISDN-UP specifies the procedures for setting up and tearing downtrunk connections utilizing CCIS signaling. ISDN-UP messages, forexample, include an Initial Address Message (IAM), an Address CompleteMessage (ACM) and an Answer Message (ANM)

[0137] SS7 specifies an Application Service Part (ASP) for performingthe functions of the presentation, session and transport layers for theTCAP and OMAP protocols. The lower four layers of the SS7 protocolcorrespond to the lower three layers (network, link and physical) of theOSI model. The lower three layers of the SS7 protocol, the networklayer, the signaling link layer and the data link layer, form theMessage Transfer Part (MTP) of SS7. The MTP is common to messages forall applications and provides reliable transfer of signaling messagesbetween network nodes. The MTP relays messages between applicationsrunning at different nodes of the network, effectively like a datagramtype service.

[0138] The SS7 network layer (lower portion of L3) routes messages fromsource to destination. Routing tables for the signaling network layerfacilitate routing based on logical addresses. The routing functionalityat this layer is independent of the characteristics of particular links.

[0139] The signaling link layer (L2) performs flow control, errorcorrection and packet sequence control. The signaling data link layer(L1) is the actual physical connection between nodes of the CCISnetwork. The signaling data link layer in CCIS provides full duplexpacket switched data communications. The signaling data link layerelement provides a bearer for the actual signaling messagetransmissions. In a digital environment, 56 or 64 Kbits/s digital pathscarry the signaling messages between nodes, although higher speeds maybe used.

[0140] At the equivalent of the OSI network layer (L3), the SS7 protocolstack includes a Signaling Connection Control Part (SCCP) as well as thenetwork layer portion of the MTP. SCCP provides communication betweensignaling nodes by adding circuit and routing information to SS7messages. The SCCP routing information serves to route messages to andfrom specific applications. Each node of the signaling network,including the various switching offices and databases in each network,is assigned a 9-digit point-code for purposes of addressing signalingmessages through the CCIS network. Both the SCCP protocol and the MTPprocessing utilize these point codes.

[0141] The SS7 messages traverse the network at all times. The messagesthemselves comprise digital serial messages that come into the STP. FIG.5 provides a graphic illustration of an SS7 message packet. The firstbyte or octet of the message is a flag, which is a zero followed by 6ones and another 0. This constitutes a unique bit pattern in the SS7protocol. The protocol ensures that this particular pattern is notrepeated until the next message. This provides a flag at the beginningof a new message. A flag at the end of a message is also providedusually in the form of the flag at the beginning of the next message,i.e., a message usually contains only one flag. The message is arrangedin 8 bit bytes or octets. These octets represent the information carriedby the message. The message contains both fixed and variable parameters.The Message Transport Part (MTP) of the SS7 message is always in thesame place. The values change but the MTP is always in the same place.

[0142] Octets 2-11 form a routing label as discussed later with regardto FIG. 4. Octet 12 contains a signaling link selection (SLS) byte usedto select specific links and/or determine the extent to which thenetwork can select specific links to achieve load sharing. Octet 13contains a Customer Identification Code (CIC) which typically is used toselect an interexchange carrier. Octet 14 contains a message typeindicator, and octets 15-N contain the actual message, in the form offixed parameters, mandatory parameters and optional parameters. Thelength of the mandatory parameters field and the optional parametersfield are variable. There would be 16 other bits that have CyclicRedundancy Codes (CRCs) in them and another flag which would constitutethe end of the SS7 message (and typically the start of the nextmessage). CRCs constitute a further error detection code which is alevel 1 function in the protocol.

[0143]FIG. 6 is a graphic illustration of the routing label of the SS7message packet. The first 7 bits of octet 2 constitute the BackwardSequence Number (BSN). The eighth bit is the Backward Indicator Bit(BIB) which is used to track whether messages have been receivedcorrectly. The length of an SS7 message is variable, Age therefore octet4 contains a message length indicator.

[0144] Octet 5 is the Service Information Octet (SIO). This indicateswhether it is a Fill In Signal Unit (FISU), Link Service Signaling Unit(LSSU) or Message Signaling Unit (MSU). MSUs are the only ones used forsetting up calls, LSSUs are used for alignment, and FISUs are fill insignals. The MSU indicator type SIO octet is formatted and encoded toserve as an address indicator, as discussed below.

[0145] The routing label includes fields for both destination relatedaddressing and point of origin addressing. The destination or ‘calledparty’ address includes octets 6, 7 and 8.′ Octets 9-11 carryorigination point code information, for example member, cluster andnetwork ID information.

[0146] In the example shown in FIG. 6, the three octets of the calledparty address contain an actual destination point code (DPC) identifiedas DPC-member, DPC-cluster and DPC-network ID information. In operation,the translation tables stored in the STP cause the STP to actually routebased on the DPC without translating any of the DPC octets into newvalues. The called party address octets (6-8), however, may carry othertypes of called party addressing information and receive differenttreatment by the STP. For example, these octets may carry a global title(GTT) and subsystem number (SSN) information.

[0147] To distinguish the types of information carried in octets 6-8,the MSU type service information octet (5) contains an addressindicator. For example, a ‘1’ value in the first bit position in thisoctet signifies that the called party address octets contain a subsystemnumber, a ‘1’ value in the second bit position in this octet signifiesthat the called party address octets contain a signaling point code. Thethird, fourth, fifth and sixth bits of the address indicator serve asthe global title indicator and are encoded to identify the presence andtype of global title value in octets 6-8.

[0148]FIGS. 7A and 7B together show a public switched telephone networksimilar to that of FIG. 3. Again, the network actually includes twolocal exchange carrier networks, 1 and 2, and the structure and generalmethods of operation of those networks are identical to those of thenetworks 1 and 2 shown in FIG. 3. FIGS. 7A and 7B, however, add a highlevel functional representation of two competing interexchange carriernetworks.

[0149] Each local exchange carrier network operates within boundaries ofa defined Local Access and Transport Area (LATA). Current laws requirethat interexchange carriers, not local exchange carriers, must transportcalls crossing the LATA boundaries, i.e., all interLATA calls. Totransport calls from one LATA to another, each interexchange carriernetwork includes a point of presence (POP) 41A, 41B in the region of thefirst local exchange carrier network 1 and a point of presence (POP)43A, 43B in the region of the second local exchange carrier network 2.Although not shown in detail, the interexchange carrier will operate anetwork of communication links and switching offices to providetransport between the POPs in different LATAs.

[0150] The interexchange carrier networks provide two-way transport forboth communication traffic (e.g., voice calls) and signaling. For CCIStype processing, the POP in each region will include both a tandem typeswitch with at least SS7 signaling point (SP) capability as well as anSTP. In each POP, the tandem connects to a switching office in therespective local exchange carrier network, and the STP connects to anSTP of the respective local exchange carrier network. In the illustratedsimplified example, the tandem switches in POPs 41A, 41B connect to thetandem 13 in network 1. The STPs in POPs 41A, 41B connect to the STP 15in network 1. Similarly, the tandem switches in POPs 43A, 43B connect tothe tandem 23 in network 2, and the STPs in those POPs connect to theSTP 25 in network 2.

[0151] Typically, each interexchange carrier will operate an SCPdatabase 45A, 45B. The SCP 45A, 45B connects to a signal transfer point(STP) at some point in each respective interexchange carrier's .network.In the illustrated example, the SCP 45B connects to an STP in POP 41B,and the SCP 45A connects to the STP in POP 43A. The SCPs provide datatranslations for 800 number calling services and the like offered by theinterexchange carriers. If an interexchange carrier chooses, one or moreof the carrier's tandems may have full SSP capability, and the SCP couldbe replaced by an ISCP to offer AIN type services to the interexchangecarrier's customers. The precise arrangement of switches, trunks, STPs,signaling links and SCPs or the like vary between interexchange carriersdepending on the traffic load each transports, the sophistication ofservices provided, etc.

[0152]FIG. 8 is a simplified block diagram of an electronic programcontrolled switch which may be used as any one of the SP or SSP typeswitching offices in the systems of FIG. 3 or FIGS. 7A-7B. Asillustrated, the switch includes a number of different types of modules.In particular, the illustrated switch includes interface modules 51(only two of which are shown), a communications module 53 and anadministrative module 55.

[0153] The interface modules 51 each include a number of interface units0 to n. The interface units terminate lines from subscribers′ stations,trunks, T1 carrier facilities, etc. Where the interfaced circuit isanalog, for example a subscriber loop, the interface unit will provideanalog to digital conversion and digital to analog conversion. Theinterface modules for the analog lines also include dial pulse detectorsand dual tone multifrequncy (DTMF) detectors. Alternatively, the linesor trunks may use digital protocols such as T1 or ISDN. Each interfacemodule 51 also includes a digital service unit (not shown) which is usedto generate call progress tones.

[0154] Each interface module 51 includes, in addition to the notedinterface units, a duplex microprocessor based module controller and aduplex time slot interchange, referred to as a TSI in the drawing.Digital words representative of voice information are transferred in twodirections between interface units via the time slot interchange(intramodule call connections) or transmitted in two directions throughthe network control and timing links to the time multiplexed switch 57and thence to another interface module (intermodule call connection).

[0155] The communication module 53 includes the time multiplexed switch57 and a message switch 59. The time multiplexed switch 57 provides timedivision transfer of digital voice data packets between voice channelsof the interface modules 51 and transfers data messages between theinterface modules. The message switch 59 interfaces the administrativemodule 55 to the time multiplexed switch 57, so as to provide a routethrough the time multiplexed switch permitting two-way transfer ofcontrol related messages between the interface modules 51 and theadministrative module 55. In addition, the message switch 59 terminatesspecial data links, for example a link for receiving a synchronizationcarrier used to maintain digital synchronism.

[0156] The administrative module 55 includes an administrative moduleprocessor 61, which is a computer equipped with disc storage 63, foroverall control of operations of the switching office. Theadministrative module processor 61 communicates with the interfacemodules 51 through the communication module 55. The administrativemodule 55 also includes one or more input/output (I/O) processors 65providing interfaces to terminal devices for technicians such as shownat 66 in the drawing and data links to operations systems for traffic,billing, maintenance data, etc. A CCIS terminal 73 and an associateddata unit 71 provide a signaling link between the administrative moduleprocessor 61 and an STP of the SS7 signaling network, for facilitatingcall processing signal communications with other central offices (COs)and with one or more of the SCPs and/or the ISCP 17.

[0157] As illustrated in FIG. 8, the administrative module 55 alsoincludes a call store 67 and a program store 69. Although shown asseparate elements for convenience, these are typically implemented asmemory elements within the computer serving as the administrative moduleprocessor 61. For each call in progress, the call store 67 storestranslation information retrieved from disc storage 63 together withrouting information and any temporary information needed for processingthe call. For example, for a switch based Centrex type service, the callstore 67 would receive and store extension number translationinformation for the business customer corresponding to an off-hook lineinitiating a call. The program store 69 stores program instructionswhich direct operations of the computer serving as the administrativemodule processor.

[0158] Of particular note, the translation data in the disc storage 63includes translation information needed to address messages fortransmission through the signaling network. In particular, when theswitch needs to send a message through the SS7 network to a particularnode, the data from the disc storage 63 provides the global title and/orpoint code for the message destination.

[0159]FIG. 9 depicts the functional elements of one of the STPs shown inthe networks of FIGS. 3, 7A and 7B. As shown, the STP comprisesinterface modules 81, a packet switch fabric 83 and an administrativemodule 85. The interface modules 81 provide the physical connections tothe two-way data links to the switching systems, SCPs, ISCPs and otherSTPs. Typically, these links provide two-way 56 kbits/s or 64 kbits/svirtual circuits between nodes of the CCIS signaling network. Themodules provide a two-way coupling of SS7 data packets, of the typeshown in FIG. 3, between the actual data links and the packet switchfabric. The packet switch fabric provides the actual routing of packetscoming in from one link, through one of the interface modules 83 backout through one of the interface modules 81 to another data link. Thepacket switch fabric 83 also switches some incoming messages through tothe administrative module 85 and switches some messages from theadministrative module 85 out through one of the interface modules 81 toone of the data links.

[0160] The administrative module 65 includes an administrative moduleprocessor 87, which is a computer equipped with RAM 91 and a programstore 89, for overall control of operations of the switching office.Although shown as a logically separate element, the program store 89typically is implemented as memory within the computer serving as theadministrative module processor 87. The administrative module processor89 provides control instructions to and receives status information fromthe operation control element (not shown) within the packet switchfabric 83. The administrative module processor 87 also transmits andreceives some messages via the packet switch fabric 83 and the interfacemodules 81. The administrative module 55 also includes one or moreinput/output (I/O) processors 65 providing interfaces to terminaldevices for technicians such as shown at 66 in the drawing and datalinks to operations systems for traffic recording, maintenance data,etc.

[0161] The program store 69 stores program instructions which directoperations of the computer serving as the administrative moduleprocessor 87. The RAM 91 stores the translation tables used to controlrouting and/or processing of messages through the STP. The RAM may beimplemented as a disc storage unit, but preferably the RAM comprises alarge quantity of semiconductor random access memory circuits providingextremely fast access to information stored therein.

[0162] The ISCP 17 is an integrated system, as shown in FIG. 10, Amongother system components, the ISCP 17 includes a Service ManagementSystem (SMS) 291, a Data and Reporting System (DRS) 295 and the actualdatabase referred to as the Service Control Point (SCP) 293. The ISCPalso typically includes a terminal subsystem referred to as a ServiceCreation Environment or SCE 292 for programming the database in the SCP293 for the services subscribed to by each individual customer. Thecomponents of the ISCP are connected by an internal, high-speed datanetwork, such as a token ring network 297.

[0163] Referring to FIG. 11 there is shown the architecture of asimplified telephone network of the type shown in FIGS. 3, 7A and 7B asit may currently be utilized for a typical form of transoceanictelephone communication. The subscriber at telephone station 100 in theUnited States, desiring to make a telephone call to a foreign country,such as Japan, is connected to originating switching office 102 which isSSP equipped as indicated at 104. The switching office 102 is here shownby way of example as connected to tandem office 106 by a trunk 108. Thetandem office has SS7 signaling capability and functions as a serviceswitching point as indicated at 110. For simplicity the tandem office ishere shown as connected by trunk 112 to an interexchange carrier pointof presence (POP) 114. The interexchange carrier switch at the POP isalso SSP equipped as shown at 116. The connections from the telephonestation 100 and the interexchange carrier point of presence are madethrough the use of common channel signaling over the CCIS network whichis here illustrated as including a signal transfer point (STP) connectedby data links to the signal switching points 104, 110, and 116. Thesignal transfer point 118 is also connected by data link to an ISCP 120.

[0164] The use of common channel signaling to effect connection to thedestination ends at the point of presence of the interexchange carrier.The interexchange carrier provides connection to the destinationtelephone station 122 via the satellite link indicated at 124 andforeign switching office 126. The foreign switching office 126 is thepoint of connection for the Japanese network satellite link. From theswitching office 126 connection is made to the destination or endswitching office 128 and thence to the Japanese telephone station 122.While the connection between the satellite point of connection switchingoffice 126 and the destination or end switching office 128 has beenshown as direct it will be understood by those skilled in the art thatthere may or may not be one of more intermediate switching offices. Inthe absence of common channel signaling beyond the United Statesinterexchange carrier point of presence 114, in band signaling must beused with its resulting deficiencies.

[0165]FIG. 12 illustrates in simplified block diagram form thearchitecture of a system capable of overcoming this disadvantageaccording to one preferred embodiment of the present invention.Referring to that figure there is shown a telecommunications systemcapable of effecting the transoceanic connection of FIG. 11 withoutincurring the deficiencies inherent in that system and methodology. FIG.12 illustrates in its upper portion substantially the same network asshown in FIG. 11 in a different layout and the same reference numeralshave been used to refer to the same elements. However FIG. 12 includesadditional features to implement end to end control signaling through avirtual link that may be accessed without construction of any new widearea network facilities.

[0166] According to the embodiment of the invention illustrated in FIG.12 the originating end switching office SSP 104 at switching office 102is associated with an internetwork server module 130. Since thepreferred internetwork is the Internet the server module 130 issometimes referred to as an Internet module. The server 130 is connectedby a data link 132, which may be an SS7 link, to the signal transferpoint (STP) 118. The actual connection need not be to the specific STP118 so long as the server is connected to the SS7 CCIS network of theLEC which serves the calling station 100. The server 130 is alsoconnected by data link 134 to the world wide internetwork shown as acloud 136. The internetwork 136 is preferably the network commonly knownas the Internet as presently described in further detail. The far end ofthe Internet cloud as shown in FIG. 12 is connected via a data link 138to a server module 140 which is connected to the foreign switchingoffice 126 SSP 142 by data link 144. It is assumed that the foreignswitching office is in a telephone network equipped with a commonchannel signaling system which provides essentially the samecapabilities as the SS7 network, as is the case with the Japanesetelephone system. Thus FIG. 12 shows connection to SSP 142, STP 148, andSSP 146 in the end switching office 128. Alternatively, the commonchannel signaling capability may be furnished by F link connectionbetween the switching offices as shown at 150.

[0167] The functional architecture of one embodiment of an InternetModule for use in this system is shown diagrammatically in FIG. 13. TheInternet Module, generally indicated at 83, includes a router 85 of thetype now generally used in Internet practice, such as shown in FIG. 13.For performing some functions which may be utilized in the system ofFIG. 12 the router may be provided with an interface with processingcapability as illustratively shown at 87. Connected to the router are aDomain Name Service (DNS) server 89 and a Dynamic Host ConfigurationProtocol (DHCP) server 91 of the type conventionally used by InternetService Providers in existing Internet Service. The router interface isconnected to the STP and to the CCIS network while the router isconnected to the Internet.

[0168] The Internet had its genesis in U.S. Government (called ARPA)funded research which made possible national internetworkedcommunication systems. This work resulted in the development of networkstandards as well as a set of conventions for interconnecting networksand routing information. These protocols are commonly referred to asTCP/IP. The protocols generally referred to as TCP/IP were originallydeveloped for use only through Arpanet and have subsequently becomewidely used in the industry. TCP/IP is flexible and robust, in effect,TCP takes care of the integrity and IP moves the data. Internet providestwo broad types of services: connectionless packet delivery service andreliable stream transport service. The Internet basically comprisesseveral large computer networks joined together over high-speed datalinks ranging from ISDN to T1, T3, FDDI, SONET, SMDS, OT1, etc. The mostprominent of these national nets are MILNET (Military Network), NSFNET(National Science Foundation NETwork), and CREN (Corporation forResearch and Educational Networking). In 1995, the Government AccountingOffice (GAO) reported that the Internet linked 59,000 networks, 2.2million computers and 15 million users in 92 countries. It is presentlyestimated that the growth of the Internet is at a more or less annualdoubling rate.

[0169] Referring to FIG. 14 there is shown a simplified diagram of theInternet. Generally speaking the Internet consists of Autonomous Systems(AS) which may be owned and operated by universities and researchorganizations and the like. Three such Autonomous Systems are shown inFIG. 314 at 310, 312 and 314. The Autonomous Systems (ASs) are linked byInter-AS Connections 311, 313 and 315. Corporate Local Area Networks(LANs), such as those illustrated in 328 and 330, are connected throughrouters 332 and 334 and links shown as T1 lines 336 and 338. Laptopcomputers 340 and 342 are representative of computers connected to theInternet via the public switched telephone network (PSTN) are shownconnected to the AS/ISPs via dial up links 344 and 346.

[0170] In simplified fashion the Internet may be viewed as a series ofrouters connected together with computers connected to the routers. Inthe addressing scheme of the Internet an address comprises four numbersseparated by dots. An example would be 164.109.211.237. Each machine onthe Internet has a unique number which constitutes one of these fournumbers. In the address the leftmost number is the highest number. Byanalogy this would correspond to the ZIP code in a mailing address. Attimes the first two numbers constitute this portion of the addressindicating a network or a locale. That network is connected to the lastrouter in the transport path. In differentiating between two computersin the same destination network only the last number field changes. Insuch an example the next number field 211 identifies the destinationrouter. When the packet bearing the destination address leaves thesource router it examines the first two numbers in a matrix table todetermine how many hops are the minimum to get to the destination. Itthen sends the packet to the next router as determined from that tableand the procedure is repeated. Each router has a database table thatfinds the information automatically. This continues until the packetarrives at the destination computer. The separate packets thatconstitute a message may not travel the same path depending on trafficload. However they all reach the same destination and are assembled intheir original order in a connectionless fashion. This is in contrast toconnection oriented modes such as SS7, frame relay and ATM or voice.

[0171] Referring to the embodiment of the invention illustrated in FIG.12 an example of the operation of the system is now described. When thecalling party at telephone station 100 dials the number of the desiredforeign party, such as the telephone station 122 in Japan, theoriginating end office switch 102 and SSP 104 recognizes the call asdirected to another switching office, suspends the call, formulates anSS7 packet message, and sends the message to the nearest STP 118. TheSTP analyzes the point code information in the packet and routes thepacket according to the translation table stored within the STP. Thattranslation table recognizes the foreign prefix as one requiringmodified common channel signal handling and directs the packet to theInternet Module 130 for transmission over an Internet route. TheInternet Module performs the necessary address determination from theinformation in the packet, adds the appropriate addressing andinstructional overhead to encapsulate the packet in one or more TCP/IPpackets, and transmits the packet or packets on to the Internet. TheInternet uses a connectionless protocol and thus if multiple TCP/IPpackets are transmitted they may or may not travel the same route andmay or may not arrive in the same order at the destination server orInternet Module. However the destination Internet Module 140 willperform its TCP/IP function, strip the overhead, reform the original SS7packet and deliver it to the SS7 capable control network of thedestination telephone system. That network operates in its designedmanner to send the message via the foreign SS7 network to the endswitching office that serves the destination telephone line, i.e., tothe terminating end office 128 in the illustrated example. Theterminating end office determines whether or not the called station 122is busy. If the called station is busy, the terminating end office soinforms the originating end office via SS7 signaling in the foreign CCISnetwork, TCP/IP signaling in the Internet, and SS7 signaling in theoriginating switching system. The originating end office provides a busysignal to the calling station. If the called station 122 is not busy,the terminating end office 128 so informs the originating end office. Atelephone connection is then constructed via the trunks, switchingoffices, and satellite link between the calling and called stations.

[0172] While the illustrative call did not require a higher level ofcontrol than that available from the STP, the system is, capable ofproviding service features which require centralized program controlfrom a higher level control point. Such control may be obtainedaccording to the invention either from the ISCP which controls the CCISnetwork of the originating telephone network or, alternatively, from acentral control such as the controller 150 connected to the Internet.Such a controller may emulate an ISCP and communicate with the Internetthrough a server or Internet Module similar to that shown and describedin connection with FIG. 13.

[0173]FIG. 15 illustrates a further embodiment of the invention whichvirtually eliminates the need for reliance on the CCIS network of theoriginating telephone network. The network shown in FIG. 15 is similarto that shown in FIG. 14 with the difference that the link 132 betweenserver or Internet Module 130 and STP 118 in FIG. 14 has been eliminatedand a data link has been established directly from the SSP 104 for endoffice 102.

[0174] In operation the caller dials the number of the called stationcomplete with the foreign prefix. The SSP 104, programmed to recognizepredetermined prefixes as an action trigger, momentarily suspendsprocessing of the call and formulates a message to be sent to theInternet Module or server 130. The query message content and format issimilar to that of the message sent from the STP 118 to the server 130in the embodiment of the invention described in connection with FIG. 12.It will include the called party's number and an indication, such as theautomatic number identification (ANI), of the calling station's number.It will also include an indication of call type (here, that the call isplaced to a predesignated prefix and is to be handled via Internetsignaling). This provides the Internet Module or server with anindication of the treatment the call is to receive. The Internet Modulethereupon processes the message in the manner described in detail inconnection with FIG. 12. If the called party is available a voiceconnection is set up. If the called line is busy a busy signal isprovided to the calling party.

[0175] It will be readily seen by one of ordinary skill in the art thatthe present invention fulfills all of the objects set forth above. Afterreading the foregoing specification, one of ordinary skill will be ableto effect various changes, substitutions of equivalents and variousother aspects of the invention as broadly disclosed herein. It istherefore intended that the protection granted hereon be limited only bythe definition contained in the appended claims and equivalents thereof.

1. A telecommunications system comprising in combination: a firstswitched telecommunications network including first program controlledswitching systems serving first customer premises terminals connected bylocal links to said first program controlled switching systems, saidfirst program controlled switching systems being connected by trunks andhaving a first common channel signaling system for controlling call setup to selectively establish communication connections between said firstcustomer premises terminals over said trunks; a second switchedtelecommunications network including second program controlled switchingsystems serving second customer premises terminals connected by locallinks to said second program controlled switching systems, said programcontrolled switching systems being connected by trunks and having asecond common channel signaling system for controlling call set up toselectively establish communication connections between said customerpremises terminals over said trunks; a wide area internetwork connectingspaced dissimilar networks and using transmission controlprotocols/internet program (TCP/IP) to link said dissimilar networks;and first and second interfaces having routing capabilities linking saidfirst and second switched telecommunications networks respectively tosaid wide area internetwork to establish a data link between said firstand second switched telecommunications networks for controlling call setup to selectively establish a communication connection between a firstcustomer premises terminal in said first switched communications networkand a second customer premises terminal in said second switchedtelecommunications network at least partially over said trunks.
 2. Atelecommunication system according to claim 1 wherein saidcommunications connection between said first and second switchedtelecommunications networks is at least partially wireless.
 3. Atelecommunication system according to claim 1 wherein said data linkbetween said first and second switched telecommunications networks is aconnectionless link.
 4. A telecommunication system according to claim 1wherein said data link between said first and second switchedtelecommunications networks transports TCP/IP packets encapsulatingdatagrams created by said first and second switched telecommunicationsnetworks.
 5. A telecommunication system according to claim 4 wherein atleast one of said datagrams includes an identification number of acalling customer premises terminal in one of said first and secondswitched telecommunications networks and an identification number of acalled customer premises terminal in the other of said first and secondswitched telecommunications networks.
 6. A telecommunication systemaccording to claim 5 wherein at least one of said datagrams is createdin the common channel signaling network of the switchedtelecommunications network which is connected to said calling customerpremises terminal.
 7. A telecommunication system according to claim 5wherein said internetwork is the Internet.
 8. A telecommunication systemaccording to claim 1 wherein the program controlled switching systems inat least one of said first and second switched telecommunicationsnetworks includes signal switching points (SSPs) and the common channelsignaling network in said one of said two switched telecommunicationssystems includes at least one signal transfer point (STP).
 9. Atelecommunication system according to claim 8 wherein said programcontrolled switching systems in said at least one of said first andsecond switched telecommunications networks includes a central controlpoint.
 10. A telecommunication system according to claim 1 wherein theprogram controlled switching systems in said first and second switchedtelecommunications networks includes signal switching points (SSPs) andthe common channel signaling networks in said switchedtelecommunications networks includes at least one signal transfer point(STP).
 11. A method of setting up a call between a first terminalconnected by a local link to a program controlled switching system in afirst switched telecommunications network and a second terminalconnected by a local link to a program controlled switching system in asecond switched telecommunications network comprising the steps of:responsive to the dialing of a number by said first terminal creating afirst signaling packet in a first protocol; transmitting said firstsignaling packet to a first interface to an internetwork separate fromsaid first and second switched telecommunications networks;encapsulating said first signaling packet in a transmission controlprotocols/internet program (TCP/IP) packet; transmitting said TCP/IPpacket via said internetwork to a second interface between saidinternetwork and said second switched telecommunications network;responsive to the receipt of said TCP/IP packet in said second switchedtelecommunications network, determining whether said second terminal isbusy; responsive to determining that said second terminal is not busyestablishing a communication path between said first and secondterminals via said local links and said program controlled switchingsystems in said first and second switched telecommunications networks.12. A method according to claim 11 wherein said internetwork is theInternet.
 13. A method according to claim 11 wherein said first protocolis a common channel signaling protocol.
 14. A method according to claim13 wherein said protocol is SS7.
 15. A method according to claim 11including the step of providing said TCP/IP packet with a destinationaddress based on said dialed number.
 16. A method according to claim 15wherein said destination address includes an address for said secondinterface.
 17. A method according to claim 16 including the steps ofstripping said destination address from said TCP/IP packet following itsarrival at said second interface, and delivering to said second switchedtelecommunications network at least that portion of said dialed numberidentifying said second terminal in said second switchedtelecommunications network.
 18. A method according to claim 11 includingthe steps of: responsive to determining that said second terminal isbusy creating a second signaling packet in a signaling protocol of saidsecond switched telecommunications network; transmitting said secondsignaling packet to said second interface to said internetwork;encapsulating said second signaling packet in a transmission controlprotocols/internet program (TCP/IP) packet; transmitting said TCP/IPpacket via said internetwork to said first interface between saidinternetwork and said first switched telecommunications network;responsive to the receipt of said TCP/IP packet in said first switchedtelecommunications network, transmitting to said first terminal a signalindicating that said second terminal is busy.
 19. A method according toclaim 18 wherein said signaling protocol of said second packet is thesame as said first protocol.
 20. A method according to claim 19 whereinsaid signaling protocol of said first and second packets is SS7.
 21. Amethod of setting up a call between a first terminal connected to aprogram controlled switching system in a first switchedtelecommunications network and a second terminal connected to a programcontrolled switching system in a second switched telecommunicationsnetwork comprising the steps of: responsive to the dialing of a numberby said first terminal creating a first signaling packet including dataidentifying said second terminal; transmitting said first signalingpacket to a first interface to an internetwork separate from said firstand second switched telecommunications networks; incorporating data fromsaid first signaling packet including said data identifying said secondterminal in a transmission control protocols/internet program (TCP/IP)packet; transmitting said TCP/IP packet via said internetwork to asecond interface between said internetwork and said second switchedtelecommunications network; responsive to the receipt of said TCP/IPpacket in said second switched telecommunications network, determiningwhether said second terminal is busy; responsive to determining thatsaid second terminal is not busy establishing a communication pathbetween said first and second terminals via said switching systems insaid first and second switched telecommunications networks.
 22. A methodaccording to claim 21 wherein said internetwork is the Internet.
 23. Amethod according to claim 21 including the step of providing said TCP/IPpacket with a destination address based on said dialed number.
 24. Amethod according to claim 23 wherein said destination address includesan address for said second interface.
 25. A method according to claim 24including the steps of stripping said destination address from saidTCP/IP packet following its arrival at said second interface, anddelivering to said second switched telecommunications network at leastthat portion of data from said first packet identifying said secondterminal.
 26. A method according to claim 21 including the steps of:responsive to determining that said second terminal is busy creating asecond signaling packet; transmitting said second signaling packet tosaid second interface to said internetwork; incorporating data from saidsecond signaling packet in a transmission control protocols/internetprogram (TCP/IP) packet; transmitting said TCP/IP packet via saidinternetwork to said first interface between said internetwork and saidfirst switched telecommunications network; responsive to the receipt ofsaid TCP/IP packet in said first switched telecommunications network,transmitting to said first terminal a signal indicating that said secondterminal is busy.
 27. A telecommunications system comprising incombination: a first switched telecommunications network including firstprogram controlled switching systems serving first customer premisesterminals connected to said switching systems, said program controlledswitching systems being connected by trunks and having a first controlsystem for controlling call set up to selectively establishcommunication connections between said customer premise terminals oversaid trunks; a second switched telecommunications network includingsecond program controlled switching systems serving second customerpremises terminals connected to said second program controlled switchingsystems, said switching systems being connected by trunks and having asecond control system for controlling call set up to selectivelyestablish communication connections between said customer premiseterminals over said trunks; a wide area internetwork connecting spaceddissimilar networks and using transmission control protocols/internetprogram (TCP/IP) to link said dissimilar networks; and first and secondinterfaces linking said first and second switched telecommunicationsnetworks respectively to said wide area internetwork to establish a datalink between said first and second switched telecommunications networksfor controlling call set up to selectively establish a communicationconnection between a first customer premises terminal in said firstswitched communications network and a second customer premises terminalin said second switched telecommunications network at least partiallyover said trunks.